RPG's, and for me that means AD&D 1E, actually have a lot to offer kids. I just spent part of the Christmas holiday planning a series of dungeon crawls that I can run my kids through over the next 2 weeks while on Christmas break.
First of all, AD&D is just fun. It allows one's imagination to kick into full gear to play "pretend". You're not Joe or Christine or Frank. No, for the next couple of hours, you are "Krush", the mighty fighter or "Luminesa" the wandering Magic User. How about "Baer", the beekeeping and mead making Druid.
I personally get an extra benefit for my kids because it provides me an opportunity, being the DM, to insert situations that make them learn at the same time.
I get to teach them teamwork and collaboration. How to think "outside of the box". I get to create interaction situations since I am the DM and not only am I the referee and Game Master, but I get to roleplay every other character that pops up in the game. Ranging from monsters to opponent warriors to shop owners, village citizens, etc...
This allows me to teach them communication skills with other people. How not to be rude and it's not just what you say, but how you say it that can get you cooperation or a smack on the head (figuratively).
It teaches them preparedness and coordinated action. Did they pack things like torches and tinder lighting kits in their backpacks before leaving the last town? How about fresh water? Thinking things out ahead of time, proper planning. All these things happen in a game.
Things like conserving and how to make the best use of existing resources. everything from spending money to how many arrows did you bring to hunt or fight with.
During the time I am "teaching" these kinds of things though, they are having a blast and laughing at the roleplay methods I use to convey each character they interact with.
All the while, I am having fun with my kids. I get to participate in their lives and growing up. I am so glad I kept those old books around so they could find them while rummaging bored in the basement for something to do (we keep all the board and other games in one of the rooms down there).
AD&D is good for me too personally. I am a very imaginative and idealistic person. Regardless of every year that tacks itself on to my life, that never changes. I can get lost in fantasy fiction books for hours. I can let my mind wander and probably get lost if I don't watch out.
AD&D gives me an outlet for my imagination. Writing storylines and backgrounds for adventures. Designing a dungeon or building for players to investigate. It's not just writing a story, it literally is writing an adventure.
Re-discovering AD&D this year has been one of the greatest gifts I have ever gotten.